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 Post subject: testing 226 and 227 tubes
PostPosted: Nov Thu 30, 2017 3:16 am 
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Joined: Jul Tue 07, 2015 8:07 pm
Posts: 160
Location: Philadelphia, PA
My Heathkit is showing no tests for either the 226 or the 227 type tubes. Any suggestions on alternative tests?


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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Nov Thu 30, 2017 3:35 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 36087
Location: Livermore, CA
226 and 227 is same as 26 and 27 tubes. If your tester has a 4 and 5 pin socket you should be able to test these tubes. Only difference between 226 and 26 is shape of the tube. Same with 227 and 27.

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Norm


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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Dec Sat 02, 2017 6:09 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4880
Location: 253 Blanche St. Plymouth, MI USA
Also you will need to have a tester made before 1960 most likely, as the later testers dropped the earlier large pin sockets.
To cover the whole tube era spectrum you need at least 2, one made around late 40's or up to 1955 at latest, and one made mid 60's.
Mark Oppat


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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Dec Sat 02, 2017 9:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 25772
Location: SoCal, 91387
If you have a TRF receiver that uses those tubes, you could try them in that chassis. Won't show exact readings, of course, but you could at least determine if they work.

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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Dec Sat 02, 2017 6:27 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11544
Location: S. Dartmouth MA 02748-1225 USA
Tips:

The 226 has a current hungry filament, be sure that the connections to the filament at the pins are well soldered and filament voltage is correct at the tube during testing. Allow the 226 to warm for at least 20-30 minutes if it has not been active in many years.

The 227 has variations from all manufacturers. The ceramic cathode sleeve insulator in some versions tends to get poisoned from the filament and becomes conductive to the cathode. A leaking cathode can effect some circuits causing hum and a shift in bias, often reducing gain in RF AF amps. No fix for this, tube is bad.

Both 226 & 227 are "S" bulb, early design with all support for the element at the press. Accidental bumping can shift elements enough to change characteristics, even short circuit. Bumping the tube in a gloved hand can shift elements from inertia and can possibly clear a short.

YMMV

Chas


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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Dec Wed 13, 2017 2:19 pm 
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Joined: Dec Mon 05, 2011 1:10 am
Posts: 248
A word of warning about testing the 26 / 226 / 326 tubes:

Your tester is unlikely to show you one of the biggest problems that happens with this tube: HUM. Since the filament is typically operated on AC, it's a bitch-and-a-half to get a #26 to function as an audio amplifier (typically the first audio stage after a #27 detector) without introducing a really objectionable amount of "60 cycle" hum. You can fuss with the adjustments on your radio all you want, but it's really tough to find a #26 that won't hum you half crazy. And, very few (if any) tube testers will help you find a good (minimum hummy) one. I've been through this several times with different radios, and the only way I've found is to just try a bunch of tubes in that 1st audio socket till I find the least hummy one.


^^;;^^


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 Post subject: Re: testing 226 and 227 tubes
PostPosted: Dec Mon 18, 2017 2:56 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Latham NY
What model number is your tester?


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